Conventional street lights are being replaced by more efficient and more reliable LED luminaires. The desired light intensity distribution provides the highest peak light intensity along the street with very little light intensity in the direction opposite to the street. The side of the luminaire facing away from the street is referred to herein as the “house side,” and the side of the luminaire facing the street is referred to herein as the “street side.” The light intensity in the house side direction should be just sufficient to illuminate a sidewalk or curb along the street.
Modern street lights using LEDs control the light intensity distribution using asymmetrical lenses over high power LEDs. Alternatively, conventional secondary optics are used to direct the light downward and sideways while blocking the light from being emitted in the house side direction. Such street lights have high glare when an observer looks directly at the luminaire. For example, one type of street light uses two parallel columns of eight high power white light LEDs with a separate lens over each LED. When viewed directly, 16 very bright point sources are seen. This is referred to as pixilated lighting and is aesthetically undesirable.
What is needed is an efficient luminaire using LEDs that has a controllable asymmetric light intensity distribution, such as optimized for overhead street lighting, where the luminaire has a non-pixilated pattern when viewed directly.